There exists printing apparatuses (inspection apparatuses) that inspect printed products. Such apparatuses are capable of determining whether printed images are correct. Japanese Patent Application Laid-Open No. 2006-091212 discusses a printing apparatus that checks a direction of a sheet by finding a hole in the sheet after print and determining the location of the hole in the sheet.
There also conventionally exists printing apparatuses that perform a print job that is set to insert tab sheets having projecting portion. The set of tab sheets consist of plural sheets having projecting portions at different location in sheets from one another.
However, by the conventional technique printing apparatuses cannot inspect whether tab sheets are inserted in the correct order between printed sheets while a print job is performed. For example, assume that five tab sheets 1 to 5 are inserted between printed pages while a print job is performed, the tab sheets having projecting portions at different location in sheets. The tab sheets set in a sheet feeding unit in the correct order will be inserted in the correct order when a print job is done, resulting in successive insertion of the sheets between printed pages with the tabs being arranged in sequence.
However, the tab sheets set in a sheet feeding unit in the incorrect order when the printing job is performed, results in the insertion of the tab sheets between printed pages in the incorrect order. As described above in the conventional technique, printing apparatus cannot determine the incorrect insertion of the tab sheets.